1. Field of the Invention
The present invention relates, in general, to digital data processing devices, and more particularly, to one bit digital data processing devices useful as one bit industrial control units.
2. Brief Description of the Prior Art
Recently, integrated circuit microprocessors have been developed in the semiconductor industry which provide a great deal of computing power on a single semiconductor chip alone or in conjunction with a relatively small number of supporting interface and memory chips. Such machines have typically been "byte-oriented" machines in which data and address information are processed so that all bits of a byte (for example, one byte can consist of 8 bits) are processed in parallel. Such microprocessors are programmable by means of machine instructions, or alternatively, software may be provided, including compilers, in order to permit programming by means of user-oriented programming languages. Either way, relatively skilled programmers are required in order to make optimum use of such microprocessors for many data processing applications. But there are many industrial control applications in which programmable control devices are required which may be readily programmed by mechanically-oriented service support personnel who are relatively untrained in electronics in general, and especially in the area of programming in machine language, assembly language, or user-oriented languages. Although the sophisticated byte-oriented microprocessors are well suited to solving problems involving complex manipulation or sorting of large amounts of data at high speed and at performing complex mathematical and logical computations, when programmed by skilled programmers, they are relatively unsuited for many of the "industrial control" logic operations presently performed by relay system. Relay systems are easily programmable by mechanically oriented persons untrained in the art of computer programming. For example, byte-oriented microprocessors are unsuited to such simple industrial control tasks as controlling the turning on of large numbers of lights or activating simple electro-mechanical switches such as solenoids in power control systems under program control. Many instructions are required in order to implement such a task with presently available byte-oriented microprocessors, and service personnel accustomed to relay type programmable circuits are unable to accomplish such programming tasks without additional training.